PHY 118 final study guide -chapter 4 - PHY 118 Final Study...

PHY 118 Final Study Guide: Chapter 4 I. The States of Water: a. As water changes state, it does not change substances it only changes the distances and interactions of its water molecules b. 3 States: i. Ice (Solid)– Composed of water molecules that have a low KE (cannot freely move) and are held together by molecular attractions 1. When it is heated, its molecules oscillate more rapidly, if heated enough the oscillations between the water molecules break and result in melting ii. Water (Liquid)– Composed of water molecules that are tightly packed and fast moving, but can slide past each other 1. This state is ‘fluid’ can take shape of its container 2. As water gains heat, its molecules will eventually acquire enough energy to break the remaining molecular bonds and escape from the surface, resulting in evaporation iii. Water Vapor (Gas) – Composed of widely spaced water molecules with very high rates of random motion 1. Water vapor differs from water because of its compressibility and expandability c. Latent Heat : i. Whenever water changes state, latent heat is exchanged between it and its surroundings ii. When 10 calories of heat are absorbed by 1 gram of water, the molecules vibrate faster and temperature increases 10 C d. Evaporation: i. Process of converting a liquid to a gas ii. Heat is absorbed during this process iii. Latent Heat of Vaporization – The amount of latent heat that gives the water molecules the energy and ability to escape the surface of liquid and become a gas (Between 600 – 540 calories) e. Condensation: i. Process of converting a gas to a liquid ii. Heat is released during this process, equal to the amount absorbed during evaporation iii. Causes fog and clouds in atmosphere f. Sublimation (Solid directly to a gas) g. Deposition (Gas directly to a solid) i. Frost forms from this II. Humidity: a. The amount of water vapor in the air b. Absolute Humidity – Mass of the water vapor of a volume of air i. As air moves around, changes in temperature and pressure change its volume; this changes absolute humidity even without any additional water vapor being added to the air because the volume of air changes

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c. Mixing Ratio – Mass of the water vapor in a unit of air compared to the remaining mass of dry air i. Not effected by changes in pressure or temperature because it is measured in units of mass d. Relationship Between Vapor Pressure and Saturation : i. Vapor Pressure – The portion of atmospheric pressure created by the

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